At week 0 there was no significant difference in antibody levels against the SARS-CoV‐2 RBD of the spike protein between the healthy controls and the patient cohort (HC median: 455 BAU/ml, IQR 253.8–702 BAU/ml vs. IEI/MBL deficiency median: 375.5 BAU/ml, IQR 70.93–850 BAU/ml; p = 0.632). This evidence concerns the gene MBL2 and hyperinsulinemic hypoglycemia, familial, 4.